Evidence of Neutrino Oscillation from SuperKamiokande and K2K

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Evidence of Neutrino Oscillation from
Super-Kamiokande and K2K
Jen-Chieh Peng
University of Illinois

• Neutrino physics at Super-Kamiokande
• Detector overview
• Atmospheric neutrinos
• Solar neutrinos
• Neutrinos from supernova and gamma-ray burst
• Long baseline K2K neutrino experiment
• Near detector and neutrino source
• Results from K2K
• Future Plans

Workshop on Neutrino Physics, November 28-29,
Hong Kong
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Super-Kamiokande Water Cherenkov Detector

• 1000 meters underground
• 41 meters high and 39 meters in diameter
• 50,000 tonnes of water
• 11,200 20-inch photomultiplier tubes
• Measure Cherenkov rings produced by e and µ

BaBar

Belle

• e/µ separation based on characteristics of the
  Cherenkov ring
• Energy of e/µ determined from ring radius

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Atmospheric Neutrinos
R 1 if no oscillation

Result from Super-Kamiokande
R 0.63 0.03 0.05 (sub-GeV e,µ) R 0.65
0.05 0.08 (multi-GeV e,µ)
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Zenith Angle Dependence

(Predictions for sin22? 1.0, ?m2 2.5 x 10-3
ev2 )
Blue no oscillation Red sin22? 1.0, ?m2
2.5 x 10-3 ev2
(Y. Hayato, HEP2003 talk)
L changes with zenith angle
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Tau-enriched sample

Black no oscillation
Red
(hep-ex/0209036)
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Mixing angles and ?m2

3-flavor oscillation analysis from SK sets limit
on sin2?13
Best-fit values sin22?a 1.0 ?ma2 2.0 x 10-3
ev2
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Solar Neutrino Measurement at Super-Kamiokande
Advantages

• Energy information
• Time information
• Directionality

Disadvantages

• Sensitive to higher energy neutrinos (from 8B)
• Limited energy resolution

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Solar Neutrino Measurement at Super-Kamiokande

Angle between electron direction and sun-earth
direction
Variation of sun-earth distance
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Solar Neutrino Measurement at Super-Kamiokande

An overall flux suppression with weak energy
dependence
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Solar Neutrino Measurement at Super-Kamiokande

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Time-Dependence of Solar Neutrino Flux

Data from Super-Kamiokande (hep-ex/0306002)
Data from 37Cl experiment
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Search for Anti-neutrinos from the Sun
How can be produced in the Sun?
Spin-flavor precession

• Majorana neutrino
• Non-zero neutrino magnetic moment
• Large magnetic field in the Sun

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Search for Neutrinos from Other Astrophysical
Sources
Gamma Ray Bursts (GRB)

Search for neutrinos correlated with 1371 GRBs
observed by BATSE
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Search for Neutrinos from Other Astrophysical
Sources
Supernova Relic Neutrinos (SRN)
SN1987A observed at Kamiokande

Upper limit of 20 to 130 cm-2 s-1 Exclude
certain SRN model
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K2K Long-Baseline Neutrino Oscillation Experiment
To check atmospheric neutrino result from
Super-Kamiokande using accelerator neutrino source
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K2K Long-Baseline Neutrino Oscillation Experiment
Measured neutrino spectrum
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K2K Long-Baseline Neutrino Oscillation Experiment
Angular and momentum distribution of muons
measured at the near K2K detector
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K2K Long-Baseline Neutrino Oscillation Experiment
Black no oscillation Red with oscillation
K2K result is consistent with SK. More data are
being taken
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JHF-SuperKamiokande Neutrino Oscillation
Experiment
A major goal is to determine ?13
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Hyper-Kamiokande Detector ?
1 mega-ton detector consisting of 14 sub-detector
(70 kilo-ton each)
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Summary

• Evidence for neutrino oscillation is observed
  from the zenith angle dependence of atmospheric
  neutrino signals measured at Super-Kamiokande.
• Preliminary results from K2K experiment are
  consistent with the atmospheric neutrino
  oscillation result from Super-Kamiokande. More
  data are forthcoming.
• Super-Kamiokande data provide some constraints on
  the magnitude of ?13. Future experiment
  (JHF-SuperKamiokande) has been proposed to
  measure ?13 with improved sensitivity. Other
  experiments sensitive to ?13 are clearly of
  interest.
• Neutrino experiments address some of the most
  important mysteries in particle and astrophysics,
  as demonstrated by the extremely successful
  Super-Kamiokande experiment